1. The Field of the Invention
The present invention relates to concentrated curing compositions for use in initiating or accelerating curing endodontic sealer and filler compositions placed in a person's root canal. In addition, the invention relates to kits that include a microdose container filled with a concentrated curing composition used to coat or impregnate a dental tool for use in initiating or accelerating curing of an endodontic sealer or filler composition.
2. The Related Technology
In an endodontic root canal procedure, the root canal is typically cleaned using special root canal tools and irrigation devices. Following such a root canal procedure, it is important to fill and seal the evacuated root canal to preserve the dead tooth from further decay that might compromise the integrity of the tooth and cause infection. In a typical procedure, one or more soft, resilient, needle-like inserts known as “gutta percha” cones or points are inserted in each root canal branch to at least partially seal and fill the root canal.
The term “gutta percha” refers to a rubbery material derived from natural rubber and typically blended with zinc oxide. This particular rubbery material is preferred because it is compressible, flexible and relatively soft so that it can be used to fill voids within the exposed root canal. The gutta percha cones are typically impregnated with other materials such as radiopaque solids, zinc oxide, for its medicinal properties, and other passive or active ingredients as desired.
Filling a root canal with gutta percha often requires inserting more than one gutta percha point or cone. Most root canals are narrow at the apical end and widen as they move up through the tooth. The first gutta percha point or cone is used to seal the apex and is often referred to as the master cone. Following placement of the master cone, additional gutta percha points can be added to fill the increasingly larger void of the root canal.
Experience has shown that it is impossible to completely seal a root canal using gutta percha alone. To further seal the root canal, flowable materials, such as sealing resins, are inserted into the root canal along with the gutta percha points. One feature of most sealing resins is the need to harden or cure the resin. The sealing resin remains in a liquid state until polymerized by an initiator or curing agent. Because root canals are deep and narrow, photocuring a resin deep within the root canal is not possible. A chemical curing agent must be employed. The curing agent is typically mixed with the resin just prior to inserting the resin in the root canal, thereby giving the practitioner the greatest amount of time to work before the resin hardens.
One disadvantage of chemically curable resins is that once chemical curing begins the reaction cannot be easily stopped or inhibited. Thus, a practitioner has only a limited time to work with the material once hardening begins. In theory, this window of time can be lengthened or shorted in advance by selecting the amount or type of curing agent that is mixed with the curable resin. If the time is lengthened, the hardening step may take an undesirably long amount of time once the resin is placed in the tooth. If the time is shorted, the practitioner may be rushed if the procedure turns out to be more difficult than anticipated. Thus, while the cure time can be modified, at least in theory, before the procedure begins, once curing has been initiated, curing will proceed within whatever time frame is dictated by the curing agent. Depending on the temperature, extent of mixing, and other variable factors, the actual window of time in which the resin will cure may be unpredictable.
This inability to modify cure times once curing has been initiated can make certain steps of a root canal procedure difficult or impossible. For example, a practitioner may not have sufficient time to take an X-ray to determine whether the sealing material has successfully filled the entire root canal, including lateral canals and/or whether the gutta percha points have been properly positioned. Alternatively, the curing process may take too much time, thus wasting the patient's and the practitioner's time or making it necessary for the patient to return for a follow up procedure after the resin has fully hardened.
Therefore, what is needed are compositions, kits and methods that can be employed to reliably cure a curable resin placed within a person's root canal while giving the practitioner flexibility to increase or decrease the time the practitioner has to work with the resin while carrying out the dental filling procedure.